The present invention relates to the construction of glide boards and particularly to methods of mass distribution in a snow ski.
The distribution of mass along the length of an alpine ski is a key element that affects the dynamics of ski performance. The same consideration also applies to Nordic skis and snowboards. Mass distribution impacts the modal and nodal vibrational properties of the ski structure, which in turn determines how the ski handles shock and vibration.
Conventionally, skis were fashioned from solid or laminated wood. In more recent years, skis have been constructed from a core, formed of wood or foam, that is sandwiched between or encased by load carrying structural layers having a constant thickness. The structural layers may be formed of glass, carbon or polyaramide fiber reinforced resins or aluminum alloys, for example. The stiffness profile of the ski along its length, vital to performance, is conventionally obtained by varying the thickness of the core. The result of this is that the distribution of mass along the length of the conventional ski is coupled to the stiffness of the ski, both of which are determined primarily by the core thickness. A thicker core results in a larger beam formed from the load carrying layers that surround the core, and vice versa. A thinner core results in a smaller beam and less stiffness. This has meant that for conventional skis only relatively small variations in ski mass distributions are possible. It has thus been necessary to change ski length, change the mass of the ski tips, or to add external weights to alter a ski""s dynamic behavior.
Other types of conventional skis have used a split core construction, i.e., a ski core formed from first and second core layers joined by an elastomeric layer. However, these split cores are still sandwiched between or encased by load carrying structural layers, thus again coupling ski stiffness and mass distribution.
The present invention provides an elongate glide board defining a fore body portion and a rear body portion. The glide board includes a body formed from a primary core reinforced by at least one load carrying structural layer. A secondary core overlies at least portions of the body outside of the at least one load carrying structural layer. A top layer covers at least the secondary core and any exposed portions of an upper surface of the body. A base layer covers a lower outer surface of the body.
In further aspects of the invention, an elongate glide board includes a longitudinal primary core defining upper and lower surfaces. A load carrying structural layer wraps at least the upper and lower surfaces of the primary core and defines corresponding upper and lower outer surfaces. A secondary core at least partially overlies the upper outer surface of the structural layer, above the primary core. A top layer covers at least the secondary core and any exposed portions of the upper outer surface of the structural layer. A base layer covers the lower outer surface of the structural layer below the primary core.
In a further aspect of the present invention, a method of fabricating an elongate glide board is provided. The method entails wrapping at least upper and lower surfaces of a longitudinal primary core with a load carrying structural layer. The load carrying structural layer defines corresponding upper and lower outer surfaces. The method further entails overlying at least a portion of the upper outer surface of the structural layer with a secondary core. A top layer is applied over at least the secondary core and any exposed portions of the upper outer surface of the structural layer. A base layer is applied over the lower outer surface of the structural layer below the primary core.
The present invention thus provides a method to decouple mass distribution along the length of a ski from ski stiffness. The provision of a modular or secondary core positioned above the primary core, and outside of the beam formed from the structural reinforcing layers, enables the provision of increased total core thickness at desired locations along the length of the ski without a corresponding increase in ski stiffness. By constructing a ski with a secondary core disposed above the primary core and all of the major load carrying structural layers, core weight can be added to locations of the ski forward and rearward of the binding zone. In addition to determining the dynamic properties of the ski, the provision of a modular second core can reduce the effects of impact loads encountered by the ski tips.